There's A Project Working To Implement Direct3D D3D9 Over Vulkan

Many have hypothesized over implementing Direct3D over Vulkan for helping out the Linux gaming scene and as an alternative to Wine's Direct3D-to-OpenGL wrapper while a developer appears to have taken up the challenge and has been making progress in writing a Direct3D 9 compatibility layer over Vulkan.

Christopher Schaefer has been developing what he's calling "SchaeferGL" as a Direct3D 9 compatibility layer for Vulkan. While the name and OpenGL reference may seem odd, the project originally started out in 2014 with a different focus. Back then, SchaeferGL was brewing plans to rework the Gallium3D "Nine" state tracker to make it a standalone library and something that could potentially be supported upstream by Wine. He had also been brainstorming other ideas all around the concept of improving the Direct3D performance for Wine / Linux gamers.

SchaeferGL went quite for more than a year up until recently when he began reworking it for Vulkan. At the end of May he hit his first milestone of allowing a very basic D3D9 example to run with SchaeferGL.

While that post is from two weeks ago, the Git repository is quite active with being developed so far by just one individual and the most recent commit being from today. A lot of this initial open-source code though appears to have been written on Windows. While there is a heck of a lot work to go before this compatibility layer could be useful to Wine or in porting D3D games to Linux, hopefully it will pan out and could be interesting to see Direct3D running over Vulkan.